Refrigerant Compressor

ABSTRACT

In a cylinder head  104  provided on a head side of a cylinder block  101  with a valve plate  103  interposed therebetween, a suction chamber  119  is formed on the center side and a discharge chamber  120  is formed so as to encircle the suction chamber  119 . In the cylinder head  104 , an oil storage chamber  132  for storing an oil separated from a discharged refrigerant by an oil separating portion (a separation pipe  130  etc.) is provided. The oil storage chamber  132  extends in the diametric direction of the cylinder head  104  integrally with the cylinder head  104  and has an open end at the outer face of the cylinder head  104 , and the open end is occluded by an occluding member  134 . Here, the oil storage chamber  132  has a portion bulging into the suction chamber  119.

TECHNICAL FIELD

The present invention relates to a refrigerant compressor to be used fora vehicle air-conditioning system, and the like, and more specifically,relates to a cooling structure for lubrication oils.

BACKGROUND ART

In a refrigerant compressor, a lubrication oil is mixed in a refrigerantdrawn into and discharged from the refrigerant compressor, but when anoil circulation rate (OCR) to an air-conditioning system becomes high,heat exchange is prevented and the cooling performance drops.Accordingly, it is required to lower the oil circulation rate.

Therefore, a circulation oil contained in a discharged refrigerant isseparated and returned. However, since the oil separated from ahigh-temperature discharged refrigerant has a high temperature and thushas a low viscosity, lubrication performance becomes poor if such an oilis directly returned. Accordingly, it is required to cool the separatedoil.

In a compressor described in Patent Document 1, to a cylinder head inwhich a suction chamber and a discharge chamber are formed, an auxiliaryhead is attached so as to extend in the axial direction of the cylinderhead, and an oil storage chamber (chamber for retaining oil) is formedin the auxiliary head so that a separated oil is temporarily stored inthe oil storage chamber. Further, the oil storage chamber is providedadjacently to the suction chamber, so that the oil in the oil storagechamber is cooled by a low-temperature drawn refrigerant.

CITATION LIST Patent Document

-   Patent Document 1: Japanese Laid-Open Patent Application Publication    No. S58-131380

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, the refrigerant compressor described in Patent Document 1 hasthe following problems.

Since the discharge chamber is disposed in the central portion of acylinder head and the suction chamber is disposed so as to encircle thedischarge chamber, a region of the oil storage chamber adjacent to thesuction chamber is narrow relative to an oil storage space of the oilstorage chamber. Accordingly, when the oil storage amount becomes large,cooling of oil becomes insufficient.

Further, if the oil storage chamber is disposed adjacent to the suctionchamber of the cylinder head, the cylinder head as a whole extends inthe axial direction to increase the size of the compressor in the axialdirection, such being not preferred.

Under these circumstances, it is an object of the present invention toprovide a refrigerant compressor which achieves effective cooling of anoil in the oil storage chamber with a simple structure, and which cansuppress increase of size of the refrigerant compressor in the axialdirection.

Means for Solving the Problems

A refrigerant compressor according to the present invention premises aconstruction including a cylinder block that has a plurality of cylinderbores disposed in parallel to and around the axis of the cylinder block;a cylinder head that is provided on one end of the cylinder block with avalve plate interposed therebetween; pistons that are inserted from theother end of the cylinder block into the respective cylinder bores andconfigured to reciprocate in the cylinder bores to compress arefrigerant drawn from a suction chamber on the cylinder head side anddischarge the compressed refrigerant into a discharge chamber on thecylinder head side; and an oil recirculation mechanism that separates alubrication oil from the refrigerant discharged into the dischargechamber and returns the lubrication oil to a lubrication portion of thecompressor.

Here, the cylinder head has, in its inside, the suction chamber, thedischarge chamber, a suction passage for introducing a refrigerant drawnfrom an external refrigerant circuit into the suction chamber, and adischarge passage for leading out the refrigerant discharged into thedischarge chamber to the external refrigerant circuit. The suctionchamber is disposed on the center side in the diametric direction of thecylinder head, and the discharge chamber is disposed on the outer sidein the diametric direction of the cylinder head so as to encircle thesuction chamber.

Further, the oil recirculation mechanism has an oil storage chamber forstoring the separated oil. The oil storage chamber includes a tubularportion, that extends in the diametric direction of the cylinder headintegrally with the cylinder head and has an open end at the outer faceof the cylinder head, and an occluding member that occludes the openend. The tubular portion has a bulge portion bulging to the suctionchamber side.

EFFECTS OF THE INVENTION

According to the present invention, a high temperature oil in the oilstorage chamber can be effectively cooled by a low temperature drawnrefrigerant in the presence of the bulge portion into the suctionchamber side, and it is possible to suppress drop of viscosity of theoil. Moreover, since the suction chamber is disposed in the center sidein the cylinder head, it is easy to dispose the oil storage chamberadjacent thereto and so as to bulge into the suction chamber.

Further, by making the oil storage chamber bulge into the suctionchamber side and thereby shift the oil storage chamber toward thesuction chamber side, it is possible to suppress increase of the size ofthe compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a refrigerant compressor (inparticular, a variable displacement compressor) illustrating anembodiment of the present invention.

FIG. 2 is a view of a cylinder head observed from its valve-plate-sideend.

FIG. 3 is a cross-sectional view of an oil storage chamber (A-Across-sectional view in FIG. 2).

FIG. 4 is a cross-sectional view of a separation chamber.

FIG. 5 is a substantial-part cross-sectional view of a refrigerantcompressor illustrating another embodiment of the present invention.

MODES FOR CARRYING OUT THE INVENTION

Now embodiments of the present invention will be described in detail.

FIG. 1 is a cross-sectional view of a refrigerant compressor (inparticular, a variable displacement compressor) illustrating anembodiment of the present invention. Further, FIG. 2 is a view of acylinder head observed from its valve-plate-side end, FIG. 3 is across-sectional view of an oil storage chamber (A-A cross-sectional viewin FIG. 2), and FIG. 4 is a cross-sectional view of a separationchamber.

First, the basic construction of a variable displacement compressor willbe described.

A variable displacement compressor 100 includes a cylinder block 101that has a plurality of cylinder bores 101 a disposed in parallel to andaround the axis of the cylinder block 101; a front housing 102 that isprovided on one end of the cylinder block 101; and a cylinder head (rearhousing) 104 that is provided on the other end of the cylinder block 101with a valve plate (valve-port-formed member) 103 interposedtherebetween. These components as well as interposed gaskets, which arenot illustrated, are fastened together by bolts 140 to constitute acompressor housing.

In the central portions of the cylinder block 101 and the front housing102, a drive shaft 106 is provided so as to extend laterally across acrank chamber 105 formed between the cylinder block 101 and the fronthousing 102, and a swash plate 107 is disposed around the drive shaft106. The swash plate 107 is coupled via a connecting unit 109 with arotor 108 fixed to the drive shaft 106, so that the inclination angle ofthe swash plate 107 along the drive shaft 106 is variable. Here, betweenthe rotor 108 and the swash plate 107, a coil spring 110 for urging aforce to the swash plate 107 toward the minimum inclination angle isattached, and further, on the other side across the swash plate 107, acoil spring 111 for urging a force to the swash plate 107 toward adirection of increasing the inclination angle is attached.

One end of the drive shaft 106 extends through a boss portion 102 aprotruding outwardly from the front housing 102, to the outside and isconnected to an electromagnetic clutch, which is not illustrated. Here,between the drive shaft 106 and the boss portion 102 a, a shaft sealdevice 112 is inserted so as to form a sealing between the inside andthe outside of the front housing 102. The drive shaft 106 is supportedby bearings 113, 114, 115 and 116 in radial and thrust directions, sothat a drive force from an external drive source is propagated via theelectromagnetic clutch to rotate the shaft 106.

In each cylinder bore 101 a of the cylinder block 101, a single headtype piston 117 is inserted and disposed so that its head is on thecylinder head 104 side and that the piston 117 is reciprocatable. On theother end portion of the piston 117 opposite to the piston head, arectangular recess 117 a is formed, and the outer peripheral portion ofthe swash plate 107 is accommodated in the recess 117 a so that thepiston 117 and the swash plate 107 are configured to interlock with eachother via a pair of front and rear shoes 118. Accordingly, by rotationof the drive shaft 106, each piston 117 can be reciprocated in eachcylinder bore 101 a.

Inside of the cylinder head 104 is compartmented to form a suctionchamber 119 and a discharge chamber 120. The suction chamber 119 isdisposed in the center side in the diametric direction of the cylinderhead 104 (on the extended axial line of the drive shaft 106), and thedischarge chamber 120 is disposed on the outer side in the diametricdirection of the cylinder head 104 so as to be in an annular formencircling the suction chamber 119.

In the valve plate 103, suction ports 103 a through which the cylinderbores 101 a (compression chambers of the piston 117) communicate withthe suction chamber 119 in the cylinder head 104, and discharge ports103 b through which the cylinder bores 101 a (compression chambers ofthe piston 117) communicate with the discharge chamber 120 in thecylinder head 104, are formed. In each suction port and each dischargeport, a one-way valve (not illustrated) is provided.

In the cylinder head 104, a suction passage 104 a for introducing arefrigerant drawn from an external refrigerant circuit into the suctionchamber 119, and a discharge passage 104 b for leading out a refrigerantdischarged into the discharge chamber 120 to the external refrigerantcircuit, are provided. Accordingly, the suction chamber 119 is connectedto an air-conditioning system side via the suction passage 104 a and thedischarge chamber 120 is connected to the air-conditioning system sidevia the discharge passage 104 b.

In this variable displacement compressor 100, rotation of the driveshaft 106 is converted by the swash plate 107 being a conversionmechanism into reciprocal movement of each piston 117, to draw anddischarge the refrigerant. Here, the displacement can be changed bychanging the stroke of each piston 117 by adjusting the inclinationangle of the swash plate 107, and the inclination angle of the swashplate 107 is changed by the pressure in the crank chamber 105.

That is, since the inclination angle of the swash plate 107 is changedby a moment caused by pressure differences between front and back sidesof all pistons 117, it is possible to optionally control the inclinationangle of the swash plate 107 by the pressure in the crank chamber 105.

In order to achieve this control, a displacement control valve 200 isprovided in the cylinder head 104. The displacement control valve 200changes the opening degree of a gas supply passage 121 through which thedischarge chamber 120 communicates with the crank chamber 105, to adjustan introduction amount of a discharge gas into the crank chamber 105.

Further, a refrigerant in the crank chamber 105 flows into the suctionchamber 119 via a gas-extraction passage that passes through gapsbetween the drive shaft 106 and the bearings 115 and 116, a space 122and an orifice 103 c formed in the valve plate 103.

Accordingly, by adjusting the opening degree of the displacement controlvalve 200, it is possible to change the pressure in the crank chamber105 to change the inclination angle of the swash plate 107, and therebyto change the displacement. Here, the pressure in the suction chamber119 is introduced into the displacement control valve 200 via acommunication passage 123, and the displacement control valve 200adjusts the introduction amount of the discharge gas into the crankchamber 105 so that the suction chamber 119 maintains a predeterminedpressure.

Next, an oil recirculation mechanism for separating a lubrication oilfrom a discharged refrigerant and for returning the separatedlubrication oil to a lubrication portion of the compressor will bedescribed.

The oil recirculation mechanism includes an oil-separation portion forseparating an oil from the discharged refrigerant, an oil storagechamber for storing the separated oil and an oil return passage forreturning the oil from the oil storage chamber to a suction side (lowpressure region).

The discharge passage 104 b is constituted by a lead out hole 104 b 1that is an upward hole provided in an upper region of the cylinder head104 and connected to an external refrigerant circuit; a separationchamber 104 b 2 that has a cylindrical shape of which diameter isgreater than that of the lead out hole 104 b 1 and disposed below thelead out hole 104 b 1; a separation pipe 130 projecting into theseparation chamber 104 b 2 and press-fit into and fixed to the lead outhole 104 b 1; and an introduction hole 104 b 3 extending in a directionsubstantially perpendicular to the axial line of the separation chamber104 b 2 and opening along an inner wall of the separation chamber 104 b2, through which the separation chamber 104 b 2 communicates with thedischarge chamber 120.

Accordingly, a gas-state refrigerant, that is discharged from eachcylinder bore 101 a into the discharge chamber 120 and contains an oil,flows through the introduction hole 104 b 3 into the separation chamber104 b 2, and while the refrigerant whirls around the separation pipe130, an oil is separated and a gas-state refrigerant is dischargedthrough the inside of the separation pipe 130 and the lead out hole 104b 1 into the external refrigerant circuit. The introduction hole 104 b3, the separation chamber 104 b 2 and the separation pipe 130 constitutean oil separation portion for separating an oil from the dischargedrefrigerant.

In order to store the oil separated by the oil separation portion, anoil storage chamber 132 is provided.

The oil storage chamber 132 includes a tubular portion that extends inthe diametric direction of the cylinder head 104 integrally with thecylinder head 104 and has an open end at the outer face of the cylinderhead 104, and an occluding member 134 that occludes the open end. Inmore detail, the oil storage chamber (tubular portion) 132 has asubstantially cylindrical shape extending in the diametric direction ofthe cylinder head 104 so as to extend through the center of the suctionchamber 119 and obliquely across the suction chamber 119. The oilstorage chamber 132 has an open end opening downwardly at the outer faceof the cylinder head 104, and the open end is occluded by the occludingmember 134. The oil storage chamber 132 is formed so that itscross-sectional area increases toward the open end so that its oilstorage space increases toward its lower region.

The oil storage chamber 132 has a bulge portion 132 a bulging into thesuction chamber 119 for cooling a stored oil.

Since the oil storage chamber 132 is disposed obliquely across thesuction chamber 119 so as to cross the center of the suction chamber,that is so as to cross an imaginarily extended line of an axial centerof the drive shaft 106, when the cylinder head 104 is observed from thedirection of FIG. 2, most of the region from the lower region to theupper region bulges into the suction chamber 119. Further, FIG. 3illustrates a cross section (A-A cross section of FIG. 2) of the oilstorage chamber 132, which shows that an axial center of the oil storagechamber 132 formed into a substantially cylindrical shape bulges intothe suction chamber 119 so that at least a half a circumferential wallof the oil storage chamber 132 faces the suction chamber 119.

Accordingly, a high temperature oil stored in the oil storage chamber132 is effectively cooled by a low temperature refrigerant in thesuction chamber 119.

Here, by making the oil storage chamber 132 bulge into the cylinder head104, it is possible to suppress increase of size of the variabledisplacement compressor 100 caused by provision of the oil storagechamber 132, and by forming the oil storage chamber 132 into a tubularform, it is possible to limit a size-increase region.

An open end of the separation chamber 104 b 2 opens directly into aregion of the oil storage chamber 132 opposing to the occluding member134, and an oil separated in the separation chamber 104 b 2 dropsdirectly into the oil storage chamber 132 and is stored. That is, theopen end of the separation chamber 104 b 2 acts as an oil introductionhole into the oil storage chamber 132.

Meanwhile, in order that the oil separated and stored in the oil storagechamber 132 is returned to the suction side, a lower region of the oilstorage chamber 132 communicates with the suction chamber 119 via anorifice 136 that functions as an oil-returning passage and adepressurizing means.

Accordingly, the high temperature oil separated in the separationchamber 104 b 2 is stored in the oil storage chamber 132, cooled by thelow temperature refrigerant in the suction chamber 119 through the bulgeportion 132 a, and returned to the suction chamber 119 via the orifice136 by a pressure difference between the oil storage chamber 132 and thesuction chamber 119. The returned oil is drawn into the cylinder bores101 a and lubricates the inside of the variable displacement compressor100.

Here, as illustrated in FIGS. 2 and 3, the suction passage 104 a extendsin the diametric direction of the cylinder head 104 and is provided sothat an imaginary line obtained by extending the suction passage 104 ainto the suction chamber 119 crosses the bulge portion 132 a.Accordingly, a main flow of the refrigerant flowing through the suctionpassage 104 a into the suction chamber 119 directly collides with thebulge portion 132 a, and the oil stored in the oil storage chamber 132is cooled further effectively.

According to this embodiment, the oil storage chamber 132 is constitutedby a tubular portion, that extends in the diametric direction of thecylinder head 104 integrally with the cylinder head and has an open endat the outer face of the cylinder head, and an occluding member 134 thatoccludes the open end. The tubular portion has a bulge portion 132 abulging into the suction chamber 119. Accordingly, a high temperatureoil in the oil storage chamber 132 is effectively cooled by the lowtemperature drawn refrigerant, and it is possible to suppress drop ofviscosity of the oil and to suppress increase of the size of thecompressor.

Further, according to this embodiment, since the bulge portion 132 aincludes at least a lower region of the oil storage chamber 132, it ispossible to cool an oil returned to the suction side (low pressureregion) regardless of the amount of the oil.

Further, according to this embodiment, since the oil storage chamber132, that is, its tubular portion, is formed so that its cross-sectionalarea increases toward the open end that opens downwardly, even when theamount of the stored oil is small, the oil is always stored. Further, byincreasing the space of the lower region bulging to the suction chamber119 side, it is possible to securely cool an oil to be returned to thesuction side.

Further, according to this embodiment, since the oil storage chamber 132is provided so that the bulge portion 132 a crosses an axial line of thecylinder head 104 (extended axial line of the drive shaft 106), the oilstorage chamber 132 is provided so that the bulge portion 132 a passesthrough the vicinity of the center of the suction chamber 119, andaccordingly, the region bulging into the suction chamber 119 increasesto increase the cooling effect.

Further, according to this embodiment, since the oil storage chamber 132is provided laterally across the suction chamber 119, it is possible tofurther increase the cooling area and to cool the high temperature oilfurther effectively.

Further, according to this embodiment, since the suction passage 104 ais disposed so that an imaginary line obtained by extending the suctionpassage 104 a into the suction chamber 119 crosses the bulge portion 132a, heat exchange is promoted and the oil is cooled effectively.

Here, when the lubrication oil is cooled by the drawn refrigerant, thetemperature of the drawn refrigerant rises. However, since the amount oflubrication oil to be cooled is limited, the temperature rise of thedrawn refrigerant is small, and the above advantage is by far greaterthan a disadvantage due to the temperature rise.

Next, another embodiment of the present invention will be described withreference to FIG. 5.

FIG. 5 is a substantial-part cross-sectional view of a refrigerantcompressor illustrating another embodiment of the present invention.Here, elements common to those of FIG. 1 are indicated by the samesymbols and their explanations are omitted. Explanation will be made fordifferent elements.

An oil storage chamber 132 having a cylindrical shape is constituted bya lower region having a large diameter and an upper region having asmall diameter, a bulge portion 132 a is constituted by the lower region132 a 1 and the upper region 132 a 2, and the bulge portion 132 a 2 ofthe upper region is smaller than the bulge portion 132 a 1 of the lowerregion in bulge volume.

By this configuration, an oil stored in the lower region, that is to bereturned to the suction chamber 119, is effectively cooled. Further,since the upper region is smaller than the lower region in bulge volume,heat exchange through the bulge portion 32 a 2 of the upper region withthe sucked refrigerant is suppressed, and it is possible to suppressunnecessary heating of the drawn refrigerant.

Here, the oil storage chamber 132 may be formed into a taper form fromthe separation chamber 104 b 2 side toward the lower region and thebulge volume may be adjusted. Further, the oil storage chamber 132 maybe disposed so as to be sloped and the bulge volume may be adjusted.Further, the upper region of the oil storage chamber not necessarilybulges.

According to this embodiment, the bulge volume of the oil storagechamber 132 increases toward the lower region and an oil stored in thelower region, that is to be returned to the suction chamber 119, iseffectively cooled. Further, the upper region of the oil storage chamber132 does not bulge into the suction chamber 119 or the upper region issmaller than the lower region in the bulge volume. Accordingly, heatexchange through the bulge portion of the upper region with the drawnrefrigerant is suppressed, and it is possible to suppress unnecessaryheating of the drawn refrigerant.

Here, the embodiments illustrated in the drawings are only examples ofthe present invention, and it is a matter of course that the presentinvention includes not only the constructions directly illustrated inthe above embodiments, but also various improvements and modificationswithin the scope of claims usually done by a person skilled in the art.

For example, the oil separation portion is of a centrifugal separationtype employing a separation pipe 130 in the above embodiments, but theseparation pipe 130 is not necessarily employed. Further, the oilseparation portion may be of another separation type such as a collisionseparation type, or a region in the discharge chamber 120 in which anoil tends to be accumulated may communicate with the oil separationchamber 132.

Further, in the above embodiments, the oil separation chamber 132 isdisposed so as to be sloped so that the open end is on the lower side,but the structure is not necessarily limited thereto and for example,the open end may be on the horizontally lateral side.

Further, in the above embodiments, the oil separation chamber 132 isconstituted by a tubular portion having a cylindrical shape, but thetubular portion may have a prismatic tubular shape such as asubstantially quadrangular tubular shape.

Further, the suction passage 104 a may have a bulge portion bulging intothe suction chamber 119, and in this configuration, an oil is moreeffectively cooled by drawn refrigerant flow.

Further, in the above embodiments, as the oil return passage, astructure in which the oil storage chamber 132 communicates with thesuction chamber 119 via the orifice 136 is employed, but a valve may bedisposed instead of the orifice, or the oil storage chamber 132 maycommunicate with the crank chamber 105.

Further, in the above embodiments, a variable displacement compressor isemployed as the refrigerant compressor, but it may be a fixeddisplacement compressor. Further, the compressor may be a clutchlesscompressor having no electromagnetic clutch, or a compressor driven by amotor.

REFERENCE SYMBOLS

-   100 variable displacement compressor-   101 cylinder block-   101 a cylinder bore-   102 front housing-   102 a boss portion-   103 valve plate-   103 a suction port-   103 b discharge port-   103 c orifice-   104 cylinder head-   104 a suction passage-   104 b discharge passage-   104 b 1 lead out hole-   104 b 2 separation chamber-   104 b 3 introduction hole-   105 crank chamber-   106 drive shaft-   107 swash plate-   108 rotor-   109 connecting unit-   110, 111 coil spring-   112 shaft seal device-   113, 114, 115, 116 bearing-   117 piston-   117 a recess-   118 shoe-   119 suction chamber-   120 discharge chamber-   121 gas supply passage-   122 space-   123 communication passage-   130 separation pipe-   132 oil storage chamber-   132 a bulge portion-   134 occluding member-   136 orifice-   140 fastening bolt-   200 displacement control valve

1. A refrigerant compressor comprising: a cylinder block that has aplurality of cylinder bores disposed in parallel to and around the axisof the cylinder block; a cylinder head that is provided on one end ofthe cylinder block with a valve plate interposed therebetween; pistonsthat are inserted from the other end of the cylinder block into therespective cylinder bores and configured to reciprocate in the cylinderbores to compress a refrigerant drawn from a suction chamber on thecylinder head side and discharge the compressed refrigerant into adischarge chamber on the cylinder head side; and an oil recirculationmechanism that separates a lubrication oil from the refrigerantdischarged into the discharge chamber and returns the lubrication oil toa lubrication portion of the compressor, wherein the cylinder head has,in its inside, the suction chamber, the discharge chamber, a suctionpassage for introducing a refrigerant drawn from an external refrigerantcircuit into the suction chamber, and a discharge passage for leadingout the refrigerant discharged into the discharge chamber to theexternal refrigerant circuit, wherein the suction chamber is disposed onthe center side in the diametric direction of the cylinder head, whereinthe discharge chamber is disposed on the outer side in the diametricdirection of the cylinder head so as to encircle the suction chamber,wherein the oil recirculation mechanism has an oil storage chamber forstoring the separated oil, wherein the oil storage chamber includes atubular portion, that extends in the diametric direction of the cylinderhead integrally with the cylinder head and has an open end at the outerface of the cylinder head, and an occluding member that occludes theopen end, and wherein the tubular portion has a bulge portion bulging tothe suction chamber side.
 2. The refrigerant compressor according toclaim 1, wherein the bulge portion includes at least a lower region ofthe oil storage chamber.
 3. The refrigerant compressor according toclaim 2, wherein the oil storage chamber is disposed so that the bulgeportion crosses the axis of the cylinder head.
 4. The refrigerantcompressor according to claim 3, wherein the oil storage chamber isdisposed so as to cross the suction chamber.
 5. The refrigerantcompressor according to claim 1, wherein the suction passage is disposedso that an imaginary line obtained by extending the suction passage intothe suction chamber crosses the bulge portion.
 6. The refrigerantcompressor according to claim 2, wherein an upper region of the oilstorage chamber does not bulge into the suction chamber side or issmaller than the lower region in bulge volume.